Proteins Functionality & Application. Anneke Martin

Transcription

1 Proteins Functionality & Application Anneke Martin

2 Content Functionality Techno-functionality of proteins Interfacial properties Gelation properties Type of protein networks Water holding Texturizing of proteins Available methods Extrusion Industrial examples

3 Three areas of functionality Physical functionality protein structure & conformation Physiological functionality Nutritional functionality

4 Types of proteins based on structure/shape Globular proteins (e.g. b-lactoglobulin, soy protein) Fibrillar proteins (e.g. gelatin, meat) Random coil proteins (e.g. caseins) Other proteins (macropolymers) (e.g. gluten)

5 Different classes of ingredient functionality Functionality Property Example Techno-functional Solubility Bulk rheology Surface activity Sensory Solubility Precipitation Thickening Gelling Texturizing Foaming Emulsifying Binding of lipids/flavors Bio-functional Nutritional Physiological Digestibility Allergenicity Anti-microbial ACE inhibition Opoid activity, etc.

6 Techno-functional properties of proteins Function Mechanism Food solubility hydrophilicity beverages viscosity water binding hydrodynamic size soups, gravies, dressings water binding hydrogen bonding meat/sausages, cakes, breads gelation network formation meats, sausages, pasta, baked goods elasticity emulsification foaming hydrophobic interactions disulfide crosslinks interfacial adsorption film formation interfacial adsorption film formation meat products, bakery products sausages, soups, dressings, desserts whipped toppings, cakes, mousse, nougat fat and flavor binding hydrophobic bonding bakery products

7 Solubility soy protein 0 M NaCl β-lactoglobulin [NaCl] M 0.2 M Renkema et al. Franco et al. (2011) Fluid Phase Equil 306:242

8 Changes in solubility Insolubility arises from aggregation which is caused by: Heat (unfolding exposure hydrophobic groups more attraction) Change in ph (at iso-electric point no net charge no repulsion) Enzymatic hydrolysis (exposure of hydrophobic groups more attraction) Association with non-protein compounds (lipids, flavors, polysaccharides) NB Presence of salts is needed to solubilise meat proteins!

9 Interfacial properties of proteins Most proteins have hydrophilic and hydrophobic parts Protein unfolds at interface and decreases interfacial tension Due to charge proteins act as stabiliser at the air/water and oil/water interface fat air Negative charge causes electrostatic repulsion and stabilizing effect Addition of salts (e.g. Na+) decreases repulsion

10 Interfacial properties of proteins Interface, role of protein Steric repulsion/charge Effect of e.g. salt, ph for stability Destabilisation process Practical example

11 Examples of foods with interfaces DISPERSED PHASE solid liquid gas CONTINUOUS PHASE solid liquid solid suspension: fruit ice, chocolate sol, suspension: orange juice, acidic beverages solid emulsion, gel: jellies, cheese, processed meat products emulsion: milk, mayonnaise, margarine, french dressing gas aerosol aerosol solid foam: foam candy, bread, baked products foam: meringues, whipped cream, beer foam

12 Sausage emulsion comminuted meat Contains ~30% fat present in small droplets Stable homogeneously distributed fat droplets are positive for juiciness & tenderness

13 Gelation properties (globular proteins) Heat treatment unfolding aggregation gelation Gelation kinetics, type of gel and gel strength are a.o. influenced by: - temperature-time - ph - presence of salts - protein concentration NOT every protein denatures and forms gels!

14 Gelation properties MOLECULAR DENATURATION/ AGGREGATION GELATION NETWORK gelatin whey protein soy protein

15 Mechanisms of network formation Heat-induced gels High Temperature (whey, soy, egg white) Low temperature (gelatin) Cold-set gels, pre-heat treatment followed by: Acidification (yoghurt) Enzyme induced, e.g. rennet (cheese) Addition of salts, e.g. Ca 2+ (tofu) Type of network: fine/coarse stranded particle determines rheological and eating properties High pressure induced Combination of pressure and temperature

16 Methods: from molecule to food product < 10 nm nm µm mm-cm >mm-cm Chromatography Light scattering Confocal microscopy Texture analyzer Texture analyzer Thermal analysis Electron microscopy Light microscopy Microscopy Sensory panel Circular dichroism Rheology SDS Page Information on: -structure -unfolding vs. native -denaturation temp. Information on: -aggregation -size of structures Information on: -size of structures -properties of network at small deformation -ingredient interaction Information on: -properties of network at large deformation related to eating properties -microstructure Information on: -properties of network at large deformation -sensory properties, liking

17 Typical methods Texture Analyzer large deformation eating properties Rheometer small deformation gelation kinetics Recoverable energy is high for elastic materials

18 Rheological properties protein networks Link to hardness, elasticity Structure (particle versus stranded network) versus water binding Short chains versus long chains (winegum, young versus old cheese) Typical methods TA Rheometer Microscopy Light scattering

19 Egg white protein ovalbumin Parameter [NaCl] 0.2 M - Type gel particle stranded Fracture stress (kpa) RE (%) TIFN 2013

20 Vegetarian burger (Javaanse schijf) Role of egg white protein: binding water and holding mass together Texture analyzer and sensory panel are used to determine differences TNO 2013

21 Soy protein effect of salt type Aggregates with Ca > Mg Coarseness gels MgCl 2 >MgSO 4 Both anion and cation determine structure of protein network Effect on water holding, hardness & eating properties Urbonaite (2013) TIFN

22 Water binding/holding Relevant for juiciness, tenderness Water holding capacity in meat proteins Water holding capacity in meat [gelatin] plasma [NaCl] TIFN 2013 TNO 2010

23 Eating properties Texture analyzer: hardness, elasticity, serum release Serum release during deformation is a measure for juiciness and flavour perception The perceived juiciness is the result of the amount of serum that is pushed out of the meat matrix while chewing and the ability of the tissue to bind water, which is affected by the salt content. Sausages with high serum release were perceived significantly saltier than those with little serum release Sausages with a high serum release were perceived more juicy than those with a low serum release.

24 Microstructure controls serum release Serum release relates positively to salt/flavour perception interconnected pores separate pores protein continuous system vdberg (2007) Food Hydrocoll 21:961

25 Gluten 80% of gluten consists of gliadin and glutenin Gluten are not soluble in water Gives structure to e.g. bread and pasta Forms strong reversible elastic network and entraps air bubbles during proving and baking

26 Glutenfree Gliadin fraction is said to be responsible for coeliakie Replacement of gluten by hydrocolloids in bread does not result in satisfying products Gliadin fractions can be replaced by protein particles made from whey protein or gelatin protein particles flour+water+protein Van Riemsdijk et al. (2011) J Cereal Sci

27 Replacement of meat proteins by plant protein Meat protein fibrillar structure Plant proteins globular or other protein unfolding of globular proteins and alignment of protein aggregates into fibrillar structures TUNE FUNCTIONALITY OF PROTEIN!

28 Structuring of proteins Formation of fibrillar-like structures of protein to mimic meat Electrospinning Shear cell Fibril formation at low ph Extrusion Examples: Valess, Ojah (Beeter), texturized protein (Solae)

29 Electrospinning Spinning of proteins in food-grade way is difficult For use in food fibers need to be collected and/or aligned (in progress) Upscaling of process needs attention gelatin + 15% WPI % WPI + 10% WPI Nieuwland et al TNO

30 Shear cell Flow induced structuring of 30% caseinate in combination with enzymatic crosslinking Fibrous structures of µm-mm Not performed yet with plant proteins? Scaling up? Manski et al. (2008) Food Hydrocolloids 22: 587

31 Fibril formation Extensive heating and shearing at low ph renders protein fibrils Unique property: very low critical gelling concentration Drawbacks: yield (conversion) + upscaling WPI fibrils Ovalbumin fibrils 1000 nm 1000 nm Munialo (2013)TIFN

32 Extrusion Thermal and mechanical energy input at low to medium moisture conditions Protein concentrates or flours are mixed with water, pushed through a cylinder (turning screw). Moisture is evaporated forming dry fibrous, porous granules or chunks

33 Texturized vegetable protein (TVP) Microfibrillar protein network due to unfolding, orienting and thermal crosslinking (temperature well above denaturation temp.) Dry texturized proteins with high water binding & swelling capacity

34 Extrusion of soy protein During extrusion denaturation and chemical reactions decrease solubility Moisture content affects solubility Chen et al. (2011) Food Sci Techn 44:957 28% moisture 60% moisture buffer denaturing agents to increase solubility (e.g. SDS, urea, mercaptoethanol)

35 Extrusion of other plant proteins Literature shows that pea protein can be extruded and has similar properties as extruded soy proteins Nothing available yet on extruded lupine protein Role of gluten and starch in extrusion of plant proteins under investigation in Cluster project TNO

36 Valess milk proteins + polysaccharides (alginate from sea weed) extensive mixing phase separation of biopolymers formation of structure through addition of Ca 2+ Patent by Kweldam US

37 Ojah Beeter Sold by ao Vegetarische slager Based on plant proteins (and probably polysaccharides from seaweed) glutenfree Structure formation by sheeting/lamination of pressed heated protein

38 Questions?